You can include HTML markup in the text config, that would give a similar result. The easiest way would probably just be to use a br tag in your text. Not sure if this worked in 4.0 but there's been some work on it for 4.1.

Once you change the markup as much as you have in your tpl it's barely a button anymore. You might as well just write a custom component with an overCls and a click listener.